Process for the production of multicolor photographic images



June 5 T95] J. H. COOTE 2 55 PROCESS FOR THE PRODUCTION OF MULTICOLOR 568l PHOTOGRAPHIC IMAGES Filed May 6, 1949 BLUE sENsmvE EMULSION cbmmmns FUGITWE YELLOW DYESTUFF AND'MAGENTA COLOR FORMER GREEN LIGHT BLUE LIGHT T RED iifig 1' Jr & 1' {SEPARATION 11 NEGATWE L NEGATNE' L H 0 BLUE L'\GHT W BLUE SEPARAUON EMULSION W\TH YELLOW NEGRTWE COLOR FORMER AND FUGITIVE YELLOW DYESTUFF YELLOW \MAGE FERRICYANIDE BLEACH COLOR AND S\LVER .---GREEN IMAGE -CYAN IMAGE \MAGES FINISHED IMAGES I nvenlor Patented June 5, 1951 PROCESS FOR THE PRODUCTION OF MULTI- COLOR PHOTOGRAPHIG IMAGES Jack Howard Coote, London, England Application May 6, 1949, Serial No. 91,862 In Great Britain November 28, 1945 Claims. 1

This invention relates to the production of coloured photographic images and more particularly to the production of motion pictures in colour and is a modification of that disclosed in U. S. Patent No. 2,509,232, resulting from application ser. No. 712,245, filed November 26, 1946, of which this application is a continuation-inpart.

In U. S. Patent No. 2,509,232 there is described and claimed a process for the production of a multi-colour photographic image which comprises coating a photographic base material with a first composition containing a silver halide and a colour former which is substantially non-dif fusing under the process conditions dispersed in a photographic emulsion colloid, printing from a first colour separation record, coating the printed emulsion with a second composition containing a silver halide and a second colour former of said non-diffusing type but adapted to produce a different coloured image dispersed in the same "photographic emulsion colloid as that of said first composition so as to produce, on drying, a

and the developed silver then removed.

To produce a three-colour photographic image, three successive coating and printing stages are required, each of the coating compositions containing a colour former of the said non-diffusing type and being so chosen that upon development with the same dye image-forming developer colour records of the correct hue are produced. It has now been found that when at least a three colour image is required it is possible to proceed in a somewhat different manner.

In the present invention there is first produced a starting material carrying two emulsion layers, one of which is rendered sensitive with respect to a diflerent part of the spectrum from the other. Both the emulsion layers can then be printed from the emulsion-carrying side of the starting material using appropriate colour separation negatives and light of appropriate wave 2 lengths, without interfering with the other emulsion layer.

Accordingly the present invention provides a process for the production of a multicolour image from a set of colour separation negatives which comprises printing the outer emulsion layer of a photographic material comprising a base material carrying two photographic emulsion layers on the same side of the base, each of said. layers containing a silver halide and a substantially non-diffusing colour former dispersed in a photographic emulsion colloid, one being sensitive to a diiferent part of the spectrum from the: other, from a colour separation negative using light to which said layer is sensitive and without substantially recording an image in the underlying layer, also printing from a second colour separation negative, at any stage of the process prior to coating, in the inner emulsion layer using light to which that layer is sensitive but to which the overlying layer is not sensitive, coating the outer emulsion layer with a com-position containing a silver halide and a third substantially non-diffusing colour former dispersed therein, printing in the applied emulsion layer from a third colour separation negative without substantially recording the image in the underlying emulsion layers and thereafter simultaneously developing the successively produced latent images with a developer capable of forming dyes from said colour formers and removing developed silver from the images.

As in U. S. Patent No. 2,509,232 the emulsions used contain colour formers which are substantially non-mobile under the processing conditions dispersed in a photographic emulsion colloid and in order to produce a three colour image an additional emulsion layer, also containing a colour former of that kind has to be coated upon the outer emulsion layer after the printing of both emulsion layers, printed from a colour separation negative and the three images then simultaneously developed and further processed in the same manner as that of the above mentioned U. S. Patent No. 2,509,232.

The present process can be used where three or more colour record images are to be produced.

The colour formers used according to the present invention should be substantially nondiffusing. Several methods have been developed in recent years for rendering colour formers substantially non-diffusing, the principal ones being the introduction into the molecule of the colour former of one or more groups which impart substantive properties with respect to the or the colour former may be associated with a suitable residue which is dispersed throughout the binder of the emulsion such as that of a high molecular weight water-permeable but waterinsoluble natural resin such as gum "mastic, gum dammar, gum sandarac or gum,- elei ni or waterpermeable but water-insoluble synthetic resin such as polystyrene, polymethyl methacrylate, polyvinyl acetate or a coumarone-indene resin: or the colour former may have been combined chemicallywith the residue of a sterol, that of a substance of the cyclic methane series, that of a polypeptide, that of a highly polymeric car- 'boxylic acid, that of a. polymeric material of which a-carboxylic acid is a component or that of acarbohydrate.

The emulsion layers are conveniently gelatine emulsions. of normal characteristics and preferably are emulsions of reduced gelatine silver ratio (based on the silver nitrate used in their production) of not more than 1.5 .to 1 and most preferably of approximately 1:1. As pointed out in British PatentNo. 585,477 more satisfactory adhesion between the emulsion layers as Well as avoidance of reticulation and frilling in the processing of a multilayer material is secured by the use of these ratios.

The use of emulsion layers having these colloid/silver ratios is of a special value when one or moreadditional emul sion layers are coated upon the material as happens in the processing when three or more than three colour record images are to be produced. Moreover, the use of such emulsions enables the colour images to be accommodated within a minimum of depth.

When the present process-is'to be used for the production of a'three-colour photographic image the first andzsecond latent images may be produced from .two, colour separation negatives utilising as starting material a photographic material comprising atransparent base carrying two colloid emulsion layers each containing silver halideyand a substantially non-diffusing colour former. These layers are sensitive to different parts of the spectrum, for example, the inner emulsion layer maybe sensitised with respect to green light whilst the outer emulsion layer may be a normally-blue sensitive emulsion. The emulsions are preferably the 'gelatine emulsions of reinto the outer emulsion layer a fugitive yellow dyestuff such'astartrazine, acri'fla-vine or Photophor Basic Yellow (Imperial Chemical Industries Ltd.) which prevents undue penetration of the printing light.

.A very useful starting material is shown at .(A) in the accompanying flow sheet and is one containing ,a green-sensitive inner emulsion containing a substantially non-diffusing cyan colour former and ablue-sensitive outer 4 l emulsion containing a substantially non-diffusing magenta colour former and a fugitive yellow dyestufi. It will however be understood that the order of the emulsions may be reversed and other pairs may be used.

The green sensitive emulsion is printed through the outer emulsion layer from the appropriate colour separation negative 1. e. the green separation negative using green light (B onthe flow sheet). Green light will penetrate the blue sensitive emulsion layer without being recorded therein and it will not be impeded by the presence of the fugitive dyestuff present in that layer. The outer emulsion layer can then be printed from the red separation negative using blue light which, in the presence of the fugitive dyestuff will not penetrate sufliciently deeply to affect the underlying green sensitive emulsion layer (C on the flow sheet).

Alternatively the outer emulsion layer may be first printed using blue light. This-will behave in, exactly the same way irrespective of whether it is used in'the first or second printing steps. The green sensitive emulsion layer may then be printed using green light, this will penetrate the outer emulsion layer but will not be recorded therein since this layer is onlyblue sensitive.

Instead of, or in addition to having a fugitive 'dyestuirin' the outer emulsion layer, that layer ma be printed usin ultra-violet light.

It has been found that quite good resultscan be obtained if printingin the outer emulsion layer is done using a magenta filter: this normally has a high blue transmission; and the red light which is also transmitted is quite harmless when the underlying emulsion is green-sensitized.

When the two layers have been'printed the outer emulsion 'layer is coated with an emulsion composition containing asilver halide and a substantially non-diffusing colour former so chosen that upon developing and coupling with the same dye forming developer as that to be used forthe other images, a positive colour record of correct hue is obtained and this will be the yellowcolour former with the starting material referred to above. It is preferred that the applied emulsion composition have a colloid/silver ratio (based on the silver nitrate used in its production) of not more than 1.5-:1 and conveniently the ratio may be about 1:1. This improves the adhesion between the freshly applied emulsion and the emulsions already carried by the base material. The layer is preferably coated at such a thickness as to produce, on drying, a substantially normal coating weight of silver halide, i. e. one containing from 40 to milligrams, and preferablyBO-SO milligrams of silver per square decimeter of coating. The coating composition will also contain a fugitive yellow dyestufi. In theexample shown at D on the flow sheet the applied emulsion contains a yellow'colour former and a fugitive yellow dyestufi.

When the applied emulsion layer has dried a latent image is produced therein by printing from the appropriate colour separation negative. In the example shown at E on the flow sheet this is a blue separation negative. For such printing light must be used which will not'penetrate to either of the underlying emulsion layers. In the presence of the fugitive dyestuff blue light or ultra iolet light may be used.

The three latent images are then simultaneously developed (see F on the flow sheet), either directly or by re-exposure and redevelopment.

Dev opm nt may e ca ri out d ect y in-Whic case all the images may bedeveloped, for example, in a bath containing para-diethyl-aminoaniline as colour developer. The development bath is preferably kept in a state of thorough agitation but free from aeration throughout the development. r

It is preferred, however, to. develop first with a conventional metol-hydroquinone or amidol developer. This development is controlled so as to prevent development being carried toofar in view of the intention to subsequently redevelop. The developed material is then treated with a bath containing potassium ferricyanide and potassium bromide. The image is then reexposed and developed again in the colour developer and finally the developed silver is removed. By proceedingin this way much better control of the formation of the colour images and great consistency has been found to be possible.

After development the images are bleached in an aqueous potassium ferricyanide-ammonia solution (as shown at G on the flow sheet), rinsed and then treated with strong aqueous sodium thiosulphate (as shown at H on the flow sheet). Instead of incorporating a fugitive dyestulf into the outer layer of the starting material an additional layer containing such dyestuff can be inserted between the two emulsion layers.

When more than three emulsion layers are to be employed the additional layers are added and printed in exactly the same manner as described above for the third emulsion layer. It will, however, be understood that with respect to the third and any subsequently added emulsion layer the latent images must be produced in the underlying emulsion layers prior to the coating operation.

In the above description it has been indicated that the underlying emulsion layer is green sensitised. It will, however, be appreciated that such layer need not necessarily be green sensitised, the only requirement being that it shall be sensitised to a different part of the spectrum from that to which the outer, normally blue sensitive emulsion, is sensitive and that it is thereafter printed using the appropriate light. In addition it will be appreciated that the outer layer of the two layer starting material need not be blue sensitive, it may be sensitive to any region of the spectrum other than that to which the underlying layer has been sensitised.

When the outer layer of the two layer material is only blue sensitive the coating composition may be red sensitized and in that case need not contain a fugitive yellow dyestuff. For example it may be red sensitised if neither of the underlying layers is red sensitised and the coated material is then printed from the third colour separation negative using red light and the subsequent processing is the same as that described above.

I claim:

1. A process for the production of a multicolour image from a set of colour separation negatives which comprises printing the outer emulsion layer of a photographic material comprising a base material carrying two photographic emulsion layers on the same side of the base, each of said layers containing a silver halide and a substantially non-diffusing colour former dispersed in a photographic emulsion colloid, one being sensitive to a different part of the spectrum from the other, from a first colour separation negative of said set using light to which said layer is sensitive and without substantially recording an image in the underlying layer, also printing from a second colour separation negative of said set, in the inner emulsion using light to which that layer is sensitive but to which the overlying layer is not sensitive, coating the outer emulsion layer with a composition containing a silver halide and a third substantially non-diffusing colour former dispersed therein, printing in the applied emulsion layer from a third colour separation negative of said set without substantially recording the image in the underlying emulsion layers, the first, second and third colour formers being so chosen that upon developing with a developer capable of forming dyes coloured images of correct hue are obtained and thereafter simultaneously developing the successively produced latent images with a developer capable of forming dyes from said colour formers and removing developed silver from the images.

2. A process according to claim 1, in which the emulsions have a colloid/ silver ratio, based on the silver nitrate used in their production, of not more than 1.511 and preferably of approximately 1:1.

3. A process according to claim 1 in which the photographic emulsion colloid is gelatine and the colour formers employed contain at least one long aliphatic chain and at least one solubilising group in the molecule.

4. A process according to claim 1 in which the inner emulsion layer of the starting material employed is colour sensitised and the outer emulsion layer is a normally blue sensitive emulsion containing a fugitive dyestufl.

5. A process according to claim 1 in which the inner emulsion layer of the starting material employed is colour sensitised and the outer emulsion layer is a normally blue sensitive emulsion which is separated therefrom by a layer containing a fugitive dyestufi.

6. A process for the production of a multicolour image from a set of colour separation negatives which comprises printing the outer emulsion layer of a photographic material comprising a base material carrying two photographic emulsion layers on the same side of the base, each of said layers containing a silver halide and a substantially non-diffusing colour former dispersed in a photographic emulsion colloid, one being sensitive to a different part of the spectrum from the other, from a first colour separation negative of said set using light to which said layer is sensitive and without substantially recording an image in the underlying layer, also printing from a second colour separation negative of said set, in the inner emulsion layer using light to which that layer is sensitive but to which the overlying layer is not sensitive, coating the outer emulsion layer with a composition containing a silver halide and a third substantially non-diffusing colour former dispersed therein, printing in the applied emulsion layer from a third colour separation negative of said set without substantially recording the image in the underlying emulsion layers the first, second and third colour formers being so chosen that upon developing with a developer capable of forming dyes coloured images of correct hue are obtained and thereafter simultaneously developing the successively produced latent images with a black and white developer, treating the developed images to convert the developed material to silver bromide, re-exposing, redeveloping with a developer capable of forming dyes from the colour formers and removing developed silver.

7. A process according to claim 6 in which the emulsions have a colloid/silver ratio, based on the silver nitrate used in-their production, of not more than 1.5:1 and preferably of approximately 1:1.

8. A process according to claim 6 in which the photographic emulsion colloid is gelatine and the colour formers em-ployed contain at least one long aliphatic chain and at least one solubilising group in the molecule.

9. A process according to claim 6 in which the inner emulsion layer of the starting material employed is colour sensitised and the outer emulsion layer is a normally blue sensitive emulsion containing a fugitive dyestuff.

10. A process according to claim 6 in which the inner emulsion layer of the starting material employed is colour sensitised and the outer emulsion layer is a normally blue sensitive emulsion which is separated therefrom bya, layer containing a fugitive dyestuif.

JACK HOWARD COOIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A PROCESS FOR THE PRODUCTION OF A MULTICOLOUR IMAGE FROM A SET OF COLOR SEPARATION NEGATIVES WHICH COMPRISES PRINTING THE OUTER EMULSION LAYER OF A PHOTOGRAPHIC MATERIAL COMPRISING A BASE MATERIAL CARRYING TWO PHOTOGARPHIC EMULSION LAYERS ON THE SAME SIDE OF THE BASE, EACH OF SAID LAYERS CONTAINING A SILVER HALIDE AND A SUBSTANTIALLY NON-DIFFUSING COLOUR FORMER DISPERSED IN A PHOTOGRAPHIC EMULSION COLLOID, ONE BEING SENSITIVE TO A DIFFERENT PART OF THE SPECTRUM FROM THE OTHER, FROM A FIRST COLOUR SEPARATION NEGATIVE OF SAID SET USING LIGHT TO WHICH SAID LAYER IS SENSITIVE AND WITHOUT SUB-STANTIALLY RECORDING AN IMAGE IN THE UNDERLYING LAYER, ALSO PRINTING FROM A SECOND COLOUR SEPARATION NEGATIVE OF SAID SET, IN THE INNER EMULSION USING LIGHT TO WHICH THAT LAYER IS NOT SENSITIVE, TO WHICH THE OVERLYING LAYER IS NOT SENSITVIE, COATING THE OUTER EMULSION LAYER WITH A COMPOSITION CONTAINING A SILVER HALIDE AND A THIRD SUB- 